There is no way I think that use of weed is a fad that will fade with time. It’s been around for decades.
As for the phrase “virtue signaling “I like it I think it’s funny and I think it’s accurate to describe some behavior.
I think virtue signaling came into being when so many of us started having so many discussions online. The first one to jump in to express a thought expects others to Recognize her as the good person who carries out Correct Think.
I guess I think of virtue signal as people who have not had these opinions for very long. They are probably not deeply held convictions of long-standing, are not especially well developed.